Self-diagnosing transmission system

ABSTRACT

A system transmits electric signals, electric energy or media over short distances between units movable relative to each other. The system has at least one first unit disposed along the trajectory of the movement and at least one second unit disposed for movement relative to the first unit. A diagnosis unit is associated with at least one of the units to detect the condition of at least one of said movable units and signals that detected condition to a central control unit.

This application is a continuation of application Ser. No. 10/312,525which is the National Stage of International Application No.PCT/DE01/02443, filed Jul. 2, 2001, the disclosures of which areincorporated by reference herein.

BACKGROUND OF THE INVENTION

The present invention relates to systems for transmitting electricsignals, electric power, liquids, gases and other media over shortdistances between units movable relative to each other. Depending on thetype of the movement, these are encompassed by various terms such ascontact lines, slip rings or generally rotary transmission systems.

So-called contact lines are used to transmit electric signals orelectric power with a preferably linear or slightly curved trajectory.In the event of rotary movements, these elements are referred to as sliprings. For non-contacting transmission between mated parts or unitsmovable relative to each other, various systems are known, for examplethe system described in the European Patent Application 98 907894.4-2206 and comprising a conductor-like structure composed ofdiscrete dummy elements. Moreover, so-called rotary transmitters areknown for liquids and gases, particularly in the event of transmissionbetween mated parts or units rotating relative to each other. As a rule,such transmission systems are highly important for the function of theoverall system. They are often even classified as critical components.If, for example, the signaling function would fail between the rotor andthe stator in a computer tomograph, the emitter performance of the X-raytube could no longer be controlled. As a consequence, the patient couldbe exposed to an excessive radiation dose. In the case of a craneinstallation movable along a linear path, the failure of the emergencystop device could lead to catastrophic consequences. It is thereforedefinitely necessary in all of these applications to monitor thetransmission path. This is frequently achieved by monitoring the datacommunication between the transmitter and the receiver, with a greatnumber of different components being often integrated into this datapath in its entirety. The overall system of the transmission path ishence monitored. This known concept, however, entails the disadvantagethat individual failed or faulty components cannot be located. Thisdisadvantage is substantially more serious when the fault modes ofisolated transmission components are considered. When mechanical slidingcontact arrays, especially slip rings, are used for signal transmission,various fault constellations may occur. When, in the simplest case, thesliding path is soiled, for instance, this may result in sporadicfailure events. Such faults can often still be absorbed by a systemfault correction function. As soon as the first sporadic transmissionfaults occur, it is possible in such a case to clean the system againand to repair it. When the carbon or graphite brushes are worn to amaximum extent, however, massive faults occur in transmission suddenlybecause the brushes lift off the sliding path and can no longerestablish a contact. Here, a pre-signaling period from the first failureup to total breakdown is comparatively short. The effects aresubstantially more serious in non-contacting transmission paths. When,for example, the transmitter output power decreases continuously, due toelectronic components aging, it is possible that one day the signalamplitude will drop below the input response threshold of the receiverand that data transmission is no longer possible. This may result in anabrupt system breakdown without pre-signaling interval. In the case ofliquid transmitters, the leakage of slight quantities of liquid issufficient to result in serious damage to neighboring electroniccomponents or other parts.

In the description below, no distinction is made between stationary andmovable because such a distinction is only a question of the definitionof the reference system.

SUMMARY OF THE INVENTION

The present invention is therefore based on the problem of providing asystem that is capable of diagnosing its own condition in a simple andlow-cost manner.

In accordance with the present invention, a diagnosis unit is associatedwith the movable units, which unit is capable of determining criticalparameters of the transmission unit and of communicating theseparameters further to a central analyzer unit. What is essential for theproper functioning of the diagnosis system is the aspect that isdetermines parameters relevant for the quality in transmission directlyat the site of the transmission system. For example, it is possible toperform one global measuring of the noise for assessing a completetransmission system consisting of one or several transmitter units, feedlines or connecting elements, respectively. When the noise increasesbeyond a threshold value, it is possible merely to establish that thisthreshold is exceeded but the origin of the noise cannot be located orlocalized. However, a diagnosis unit associated directly with thetransmitter unit is suitable to solve specifically this problem. Thesame is true with regard to liquid transmission systems or other mediatransmission systems, for example, where a drop in pressure is to bediagnosed.

According to a particularly expedient embodiment of the invention, adiagnosis unit is associated with at least one of the components of theelectric transmission system in the event that an electric transmissionsystem is provided. As a result, the electric transmission system can bediagnosed directly at the site of the transmitter.

Another expedient embodiment of the invention provides, in the event ofa sliding contact array, a diagnosis unit is associated with the unitincluding the mobile sliding contacts. This unit of the mobile slidingcontact, which is frequently referred to as support of the contactsprings, as a carbon brush mount or even as a brush block, supports thecontact springs, the graphite or carbon contact elements or othercontact materials. By contrast to the other contact component, i.e., thesliding path, the stronger wear mostly occurs here. For this reason, adiagnosis unit should preferably be associated at that location.

In another expedient embodiment of the invention, a diagnosis unit ispreferably associated with the receiver in the case of an activetransmission means. In the event of active systems which employelectronic components for signal transmission, the receiver is the mostcritical component because in such a case the lowest signal levels occurwith interference that can mostly not be neglected. Specifically, adiagnosis unit capable of still evaluating the signal-to-noise ratiooptionally is particularly important. An optional diagnosis unit iscapable of diagnosing the signal levels in the transmitter.

According to a further advantageous embodiment of the invention, severaldiagnosis units are interconnected by a common bus system. With thisprovision, a particularly simple architecture of the installation ispossible, particularly in rather large-size systems. Apart therefrom, asimple extension of existing systems is possible merely by the additionof further transmitter units with diagnosis units. Examples of preferredbus systems appearing to be particularly appropriate are CAN systems,Profibus, Interbus or other field bus systems.

In another expedient embodiment of the invention, transmitter units areprovided between the movable units for transmitting the signals of thebus system so that an analyzer unit is required only on one side of thetransmission system. In the case of a mechanical slip ring, for example,slip ring paths are provided for the transmission of the bus signalsbetween the mobile units. Likewise, the signals may also be transmitted,for example, via a multiplexer system in addition to other informationthat is to be transmitted. When the transmitter unit includes ahigh-speed bus system, this bus system may also be used to transmit thesignals between the movable units in a time-based multiplexing method.

According to a further expedient embodiment of the invention, at leastone diagnosis unit comprises at least a microprocessor or a microcontroller. The micro controller serves the purpose of evaluating thesensor signals or to signal measured values or signaling information toother units, respectively.

In another advantageous embodiment of the invention, optionally adisplay means is provided on the diagnosis unit to display the conditionof the transmitter preferably in an optical or acoustical manner,respectively. In a currently preferred case, the status of thetransmission system can be established directly on the diagnosis unit.Hence, an additional display unit or an additional diagnosis system,respectively, is required. For instance, signaling can be performed byaudible alarms, by a signaling tone or a succession of sounds, or evenin the output of plain language, and optionally also by an optical alarmsuch as lamps or light-emitting diodes or even by the output of a text.

According to a further expedient embodiment, at least one diagnosis unitcomprises a display to optionally display critical operating parameters,in particular, such as the period of operation, the period of operationstill remaining, the maintenance interval or, in the case oftransmission with slip contacts, the extent of wear or the contactmaterial still left. Hence, the appropriate user or the servicingengineer has immediate access to the relevant parameters of thetransmission system. Optionally, further additional information may beprovided as to the maintenance intervals or components to be exchanged.

Another embodiment of the invention provides for monitoring preferablycritical electric parameters such as signal amplitude, signal-to-noiseratio, signal shape or even an eye pattern in the case of contactingelectrical transmission. Specifically, the measurement or monitoring ofthese electric parameters permits the assessment of the fundamentalfunctional integrity of the transmission system. For example, themagnitude of the contact noise furnishes a summary value denoting thequality of the transmission system. This is certainly an informativeparameter for ensuring that electric signals are to be transmitted tothe transmission system, as the contact noise has a substantialinfluence on the transmission quality.

A further embodiment of the invention provides for monitoring preferablycritical mechanical parameters such as signal amplitude, signal-to-noiseratio, signal development or even eye patterns.

According to yet another embodiment of the invention, criticalmechanical parameters such as the condition of the contacts or thelength of the carbon brushes and physical parameters are monitored inthe case of a contacting electrical transmission. A number of physicalparameters have a substantial influence on the transmission quality,particularly in the components directly involved in the signaltransmission. A particularly good example of this is the length of thecarbon contacts in a mechanical slip ring. With a long carbon length,the carbon pressing spring is strongly compressed so that a highpressing force is achieved as well, which results in comparatively lowcontact noise. As wear progresses, the pressing force is reduced, withcontact noise exhibiting a continuous slight increase. When the carbonis now ground far beyond its wear limit, the transmission is stoppedfrom a certain point onwards. In such a case, the inventive diagnosissystem is hence envisaged for monitoring the length of the carbon and tosignal an imminent requirement to exchange the carbon in due time,before transmission fails. The monitoring of the mechanical parameterscompletes the previously described monitoring of the electricparameters. For example, it is possible to detect on the basis of themeasurement of the contact noise that the transmission system no longersatisfies the requirements. The measurement of the physical parameterssuch as the length of the carbon elements also permits the detection ofthe cause of such a behavior when, for instance, the carbon element isalready ground off excessively.

According to still another embodiment of the invention, optionallyrelevant mechanical or physical parameters are detected. Example of suchparameters may be true running or concentricity, axial eccentricity oralso the distance or the track guidance of the mobile units.Specifically, such mechanical or physical parameters have a seriousinfluence on the function, in both contacting and non-contacting datatransmission installations and particularly in media transmissioninstallations. For example, in contacting slip rings exhibiting a highnumber of revolutions, variations in height or level in an order of 0.1mm may cause such a strong contact noise that these elements can hardlybe used for signal transmission. According to the present invention, thediagnosis unit is hence equipped with sensors and appropriate analyzercircuits or algorithms to permit the detection of such variations withsensors and appropriate analyzer circuits or algorithms, respectively,which permit the detection of such variations. For example, a change inlevel or position can be expediently detected with an inductive approachsensor.

Another embodiment provides for a diagnosis unit that is so designedthat it monitors the communication between external signal sources orsinks communicating with each other by way of the transmission unit andthe associated transmission unit. Thus, not only the transmitter unit assuch is monitored, but additionally the communication path from or to anexternal signal source or signal sink, respectively, and optionally thissource as such, is integrated into the monitoring function. Such amonitoring function may be implemented, for example, by the provisionthat the signals received in the transmitter unit are already checked.Such signal check may encompass, for instance, signal amplitude, lineimpedance, spectral composition, eye patterns, or other electricparameters, respectively. This permits an even more detailed analysis offailure or potential failure sources.

According to a further expedient embodiment of the invention, at leastone diagnosis unit comprises an analyzer unit that is capable ofperforming specific statistic analyses or trend analyses, respectively.The measured values are often not informative alone. For example, thecontact noise of a mechanical slip ring unit may strongly vary. In sucha case, a statistical analysis may be made to gain a substantiallybetter insight into the behavior of the transmission system. Forexample, a value reflecting the probability of occurrence of contactresistance values could be referred to as a yardstick for the assessmentof the quality of the transmission system. Another important analysismethod is trend analysis. This approach permits the estimation of thefuture development of the properties and characteristics of atransmission system, and of whether or when measures must be taken ormaintenance must be carried out.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be described in the following by exemplaryembodiments, without any restriction of the general inventive idea andwith reference to the drawing which is referred to in all other respectsas far as the disclosure of all inventive particulars is concerned thatare not explained in more details in the text.

The sole FIGURE shows an exemplary embodiment of a system in accordancewith the present invention, which in this case is a mechanical slip ringsystem.

DETAILED DESCRIPTION OF THE DRAWING

A mechanical slip ring transmitter consists of a rotor 1 and a carbon orgraphite brush mount 3 with associated carbon or graphite elements 2 forsignal sampling. A diagnosis unit 4 is associated with the graphite orcarbon brush mount 3 or the brush block, respectively, which detects thecondition of the carbon elements 2 and communicates signalsrepresentative of that condition to a central control unit 5. Moreover,the diagnosis unit is provided with a visual display device 6 as well asa device 7 for audible signaling of the carbon element condition.

The invention claimed is:
 1. A mechanical slip ring system, comprising:a mechanical slip ring transmitter including: a rotor; and a brush mountincluding brushes, wherein the brushes are in contact with the rotor;and a diagnosis unit associated with at least one of the rotor and thebrush mount for monitoring at least one of the electrical parameters ofsignal amplitude, signal-to-noise ratio, signal shape, or eye patternfor assessment of a fundamental functional integrity of the mechanicalslip ring system.
 2. The mechanical slip ring system according to claim1, further comprising a central control unit coupled to the diagnosisunit.
 3. The mechanical slip ring system according to claim 1, furthercomprising a common bus system and wherein the diagnosis unit is coupledto the common bus system.
 4. The mechanical slip ring system accordingto claim 1, wherein the diagnosis unit includes a visual display and/oran audible signaling device.
 5. A mechanical slip ring system,comprising: a mechanical slip ring transmitter including: a rotor; and abrush mount including brushes, wherein the brushes are in contact withthe rotor; and external signal sources or sinks communicating with eachother by means of said mechanical slip ring transmitter; wherein adiagnosis unit is associated with at least one of the rotor and thebrush mount for monitoring the communication of said external signalsources or sinks for assessment of a fundamental functional integrity ofthe mechanical slip ring system.
 6. The mechanical slip ring systemaccording to claim 5, further comprising a central control unit coupledto the diagnosis unit.
 7. The mechanical slip ring system according toclaim 5, further comprising a common bus system and wherein thediagnosis unit is coupled to the common bus system.
 8. The mechanicalslip ring system according to claim 5, wherein the diagnosis unitincludes a visual display and/or an audible signaling device.
 9. Amechanical slip ring system, comprising: a mechanical slip ringtransmitter including: a rotor; and a brush mount including brushes,wherein the brushes are in contact with the rotor; and a diagnosis unitassociated with at least one of the rotor and the brush mount formonitoring at least one of the electrical parameters of signalamplitude, signal-to-noise ratio, signal shape, or eye pattern forassessment of a fundamental functional integrity of the mechanical slipring system, the diagnosis unit further comprises an analyzer unit thatis capable of performing specific statistical analyses or trend analysesof the monitored data.
 10. The mechanical slip ring system according toclaim 9, further comprising a central control unit coupled to thediagnosis unit.
 11. The mechanical slip ring system according to claim9, further comprising a common bus system and wherein the diagnosis unitis coupled to the common bus system.
 12. The mechanical slip ring systemaccording to claim 9, wherein the diagnosis unit includes a visualdisplay and/or an audible signaling device.
 13. A rotary electrictransmission system, comprising: an electric transmission unitincluding: a first component; and a second component; wherein externalsignal sources or sinks are communicating with each other by means ofsaid electric transmission unit; an electric signal or an electric poweris transmitted between the first component and the second component andwherein the first component is movable relative to the second component;and a diagnosis unit associated with at least one of the rotor and thebrush mount for monitoring the communication of said external signalsources or sinks for assessment of a fundamental functional integrity ofthe rotary electric transmission system.
 14. A rotary electrictransmission system, comprising: an electric transmission unitincluding: a first component; and a second component; wherein anelectric signal or an electric power is transmitted between the firstcomponent and the second component and wherein the first component ismovable relative to the second component; and a diagnosis unitassociated with at least one of the first component and the secondcomponent of the electric transmission unit, wherein the diagnosis unitdetermines a quality of the electric signal or the electric powertransmitted between the first component and the second component of theelectric transmission unit for assessment of a fundamental functionalintegrity of the rotary electric transmission system; wherein thediagnosis unit further comprises an analyzer unit that is capable ofperforming specific statistical analyses or trend analyses of themonitored data.